When wireless smoke detectors were introduced, they were unreliable. Most fire marshals weren’t convinced they were a good alternative to traditional hardwired systems. However, like the cell phone, wireless smoke detectors have evolved and improved exponentially in recent years. Most of today’s wireless systems are Underwriters Laboratories listed 864 to comply with National Fire Protection Association 72, National Fire Alarm Code; in some cases, they’re proving a better choice over the wired systems.
 This combination wireless photoelectric smoke and heat detector trips when temperatures reach 135° Fahrenheit. Photo courtesy of Honeywell. |
Why? It varies by situation. Gilman Village, a historical shopping area in Issaquah, Washington, with a number of buildings dating back to the 1900s, installed a wireless system because a traditional system that would have compromised its structures and exposed conduit between buildings was impractical. Buildings that contain asbestos are also good candidates for wireless systems because no drilling is required when a wireless system is installed, minimizing the need to open areas sealed for asbestos containment.
Here are five practical reasons for considering wireless systems:
- Reliability. Wireless transmitters are fully supervised for the device input and include indications for low battery and device enclosure antitamper triggers. Because wireless device transmitters send check-in messages to the system control equipment periodically throughout the day, the system is continually aware of the status of every transmitter. Wired systems are vulnerable to corrosion, especially in geographic regions near saltwater. With wireless systems, there is no risk of wire decay. The less prone to damage a system is, the more confidence the fire service has that the system will function when needed.
- Device identification. The wireless system assigns each device an identification code. By identifying each initiating device, central stations can be very specific when contacting authorities about an emergency situation. This helps authorities to better prepare a more effective response and allows them to see precise detector information on an indicator panel.
- Less room for error. With traditional systems, there can be multiple opportunities for wiring errors during installation or through routine maintenance. In large facilities such as convention centers or hospitals, you can imagine how long it could take to find the one bad connection. With wireless systems, there are no wires to break or disturb, which helps to prevent potential mistakes. Instead, the signal is transmitted on a radio frequency. If one detector should malfunction, the system pinpoints the exact device, saving time and labor. Traditional hardwired systems may be susceptible to a single-cable fault, which affects many detection devices in one area of a building. With wireless systems, there is no risk of cable fault. Wireless systems also minimize penetration through rated walls, which is crucial to maintaining structural integrity during a fire.
- Simplified approval process. It’s less complicated to get wireless systems approved because no cable continuity or ground tests are required. The plan check is not as complex: Since there is no voltage drop when initiating device cable runs, the devices do not require additional power supplies; therefore, there are no additional power supply calculations for standby time, and the follow-up and inspection process for adding equipment and making system changes after further review are also simpler. If the fire inspector determines that additional protection is required after construction, wireless facilitates adding more detectors.
- Cost savings for end users. Though not a high priority for fire departments, we should look at account cost savings as another means of customer service when making decisions. Traditional hard-wire systems can be an expensive choice because of the conduit, connectors, fasteners, power supplies, transformers, plus the time and labor involved. Wireless systems eliminate the cost of trenching, aerial cable runs, routing cable through sealed areas, and other activities that could compromise the structure of a building.
When considering approval for a wireless fire alarm system, do the following:
- Determine if the hardware is listed for this purpose.
- Collect listing sheets from Underwriters Laboratories and the California state fire marshal (CSFM).
- Verify that the system supervises transmitters for tampering and low batteries within specified times.
- Set intervals for inspection and battery replacement.
- Test the system. Certify that each device triggers the system.
As demand for faster, more reliable solutions increase, jurisdictions should also consider wireless solutions to help minimize pressure and the workload for meeting requirements when hardwire installations and maintenance present problems.
TIM PILLING is the fire marshal for Eastside Fire & Rescue in Issaquah, Washington.
